must have posted when scissor queen did it. there are tons of sites with applique tutorials. I even have a couple on youtube. it's easier to watch a video over and over again to get the hang of it than try to explain in text.

If it is machine applique, you can put some freezer paper, or even ordinary 8 1/2 x 11 typing paper in back of the fabric. Then when you rip it away the stitches stay nice because of the bit of paper that is still there.

Life is not a movie. No one is going to yell "CUT" when you make a mistake. - Anne L. Fulton

Life is 10 percent what happens to you, and 90 percent what you do about it. - Steve Harvey

A tear away or similar stabilizer under the background fabric of your appliqué block helps to prevent puckers and tunneling. You can also open up your satin stitch a bit so it isn't as dense. Of course it also doesn't looks as full that way. I often use a buttonhole or other decorative stitch along fusible appliqué pieces for avoiding puckers.

I heavily starch the backing fabric. This stabilizes enough so there are no puckers. My method is to mix a 1:1 solution of Sta-Flo liquid laundry starch and water, "paint" this solution onto yardage using a large wall painting brush, wait a couple of minutes to make sure starch has penetrated the fibers, toss in dryer, then iron with steam. When cutting my background pieces, I cut them an inch bigger just in case there is take-up during the applique process, then cut them to size after sewing; however, this really hasn't been necessary with the heavy starching.

something other than a satin stitch may be a better choice---if you like satin stitched appliques then a stablizer is a must- but a small zigzag or blanket stitch may be a nicer choice (easier too)
take some scraps and try out a few different stitches to see what you like/works better- any heavy-tight stitch will need stablizer though.
personally i really dislike satin stitched appliques even when they come out right- just not a fan of such a heavy edge- i usually do a stitch that doesn't really show-like a tiny zigzag or a blanket stitch.